Highly active antiretroviral therapy (HAART) offers patients long-term suppression of HIV replication, but it does not cure the patients because of the long lasting latent HIV reservoir- one of the major obstacles in curing HIV infection. Reactivation of latent HIV has been under intensive investigation; however, no strategy has been developed to specifically reactivate latent HIV due to limited knowledge of how the latency is maintained. We propose to perform genome- wide knockout screening to identify the host factors that are essential for HIV latency maintenance and gain comprehensive insight into the mechanism. There has been no method for performing genome-wide loss-of-function screening in cultured cells until the appearance of four recent papers that described a CRISPR-Cas9-mediated genome-wide knockout screen. We have independently developed a similar approach to perform genome-wide screening to identify the host factors that are indispensable for WNV-induced cell death, and the results show that our method can identify target genes with high specificity. Thus, we are confident that we can identify the host factors systematically to gain comprehensive insight into the mechanism of how host factors facilitate HIV latency maintenance. We will test the identified genes in different J-Lat clones to identify the host factors that might reactivate latent HIV specifically and universally, which might lead to a new therapy to eradicate latent HIV reservoir.